Leatherback turtles: going where few air-breathers dare

Story by Bryan Wallace, Duke University.
UW photo by Ed Standora.

Life in the deep sea is as far removed from a source of atmospheric oxygen as there is on Earth, but a select few animals do not let their need to breathe air limit the depths of their exploration. (No, I’m not referring to intrepid deep-sea human researchers.) These extraordinary critters frequently venture into the hostile conditions of the deep-sea, despite being vitally tied to air the above the ocean’s surface.

When you hear about deep-diving, air-breathing animals, you might first think of colossal sperm whales plunging over 1,000 meters to battle giant squid in the dark abyss. Or perhaps you think of massive elephant seals spending over an hour at depths over a half a mile down chasing prey. Maybe you’ve even heard of the deepest known diver of them all, the beaked whales, with recorded dives to over 2,000 meters. But what about turtles? Could a shelled reptile be suited for making dives where only a few whales and seals dare to go?

Leatherback turtles, like some whales and seals, possess remarkable adaptations for long and deep dives, with large onboard stores of oxygen in their blood and muscle, and special features like collapsible lungs (to avoid ‘the bends’), flexible shell (to respond to increased pressure at depth), and slowed heart rate (to conserve energy and oxygen stores). In fact, researchers have recorded leatherbacks diving to over 1,000 meters in different ocean basins (maximum reported dive was 1,230 m in the North Atlantic). Apparently, anything a whale can do, a turtle can, too.

To be clear, leatherbacks spend most of their time within the top 300 m of the ocean. These diving tendencies are likely due to leatherbacks’ air-dependence and because they feed primarily on jellyfish, like lion’s mane jellies and sea nettles, which tend to be concentrated at or near the ocean’s surface. However, leatherbacks are clearly capable of – and undertake – much more ambitious diving. The obvious question is: what are leatherbacks doing down there?

At this point, we aren’t sure what motivates a leatherback to plunge thousands of meters away from their most critical resource, but there are a few possibilities. Like other deep-divers, they might be pursuing prey. (Let’s face it; food is a strong incentive for any animal.) Perhaps they shuttle between different water temperatures in order to keep their body temperature stable, so an occasional deep dive into frigid waters could offset the heating effects of strenuous diving. Or maybe, like many other marine animals, they use the deep-sea as refuge to evade hungry predators, such as sharks and orcas.

Currently, we are using satellite telemetry to track several leatherback turtles migrating away from their Costa Rican nesting beaches to their high-latitude foraging grounds in the Eastern Tropical Pacific. Check out www.greatturtlerace.com to follow leatherbacks on their migration and to learn more about leatherbacks, the threats they face, and what is being done to protect them. Led by Stanford researcher George Shillinger, our group is analyzing leatherback dive profiles in relation to several oceanographic features to figure out just what drives leatherback diving. So far, all leatherbacks in our study have dived well beyond 300 meters on several occasions, and many have reached depths in excess of 1,000 meters. While leatherbacks have yet to reveal all of their secrets to us, hopefully our current efforts and those of our colleagues in other parts of the world will shed light on the dark side of leatherbacks’ deep-sea lives.

From left to right, pictured are Bryan Wallace (Duke University), Rotney Piedra (Director, Las Baulas National Marine Park), Carlos Diaz (Park Ranger), George Shillinger (Stanford University), and Guillermo Briseno (Park Ranger) aside one of the largest turtles in Great Turtle Race. This turtle weighs about as much as the 5 grown men sitting behind her. She laid 12 nests at Playa Grande this season before departing on her trans-Pacific migration.

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you idiots i cant believe you would ever do such a thing i for one am a major turtle lover you wouldn’t believe how much i love turtles. And for you to do that tou guys a pure evil!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Sham Sham on you. God despises you why would you ever hurt an animal!!!!!!!!!!!!!
If I knew where you were and if I had a car i would go hurt you as much a you hurt the poor turtle they never did anything to you so why should you punish them for being the largest turtle or the smallest turtle in the world it not their fault!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I♥Turtles but I HATE YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Katie

These researchers put the soft harness-type transmitter on the turtle because you can’t poke a regular transmitter into her skin. It does not bother the turtle. The signals help them track the turtle’s migration so they can learn more about her and help CONSERVE her species.

Hi All:
It’s great to see that people are still posting comments to this story! Thanks for your interest! As a reminder, I’ve posted a follow-up story to this one (check out post #34 for the link).

I want to address some of the comments that have voiced concern over whether we are hurting the turtles. To be very clear, we love the turtles more than anyone else on Earth does. We have dedicated our lives and our professional careers to is SAVING turtles. So, while the photo above might look like we’re doing something to hurt the turtle, that ‘backpack’ is carrying a tracking device that has allowed us to follow her (and many of her fellow turtles) as they migrate across the eastern Pacific Ocean (Check out my other post to see where this turtle went!). This information is absolutely critical to finding out where they go, when, why, and what we need to do to make sure they can do so safely.

Brian Wallace – you are so patient and understanding of the harsh comments that are obviously made by young and uninformed individuals that did not bother to read the article. Thank you all for your dedication to educating the world and saving the letherback. We use your turtle race web site in our third grade class here in maumee ohio to teach students about the need for conservation and awareness.

How far north do these things come? As a Commercial Fisherman in Alaska I’ve seen a whole lot of strange things come up from the top all the way to the bottom. Even pulled up the head off of a Model A Ford once (probably used as an anchor once), but been splattered many, many times with small jellyfish. I’d love to see some turtles up here that would eat the darn things!

To Susan: That’s great to hear that info and enthusiasm about the turtles has made it all the way to Maumee, OH! I was born and raised in Ohio myself, so I love to hear that the word is out in the ‘heart of it all’!!!

To Mia: yes it is.

To ‘borealfox’: I would love to hear more about the ‘strange things’ you’ve seen in your work. I’m sure the Model A Ford is only the beginning! While it wouldn’t be impossible for leatherbacks to get all the way up to Alaska, it isn’t very common. I think there have been very sporadic sightings over the years that far north, but leatherbacks are typically limited to the Pacific NW USA and BC, Canada. But rest assured that you aren’t the only one who would love to see more leatherbacks and fewer jellyfish!

I’ve recently joined a sea turtle watch program in Walton County, FL,and this Thursday I’m giving a presentation to my Kiwanis Club all about the turtles. If you have any advice or facts you’d like me to impart to the Kiwanians, I’d be happy to do so!

On July 1, an appeal for protection was filed before the Constitutional Court by the Playa Grande Neighbors Association, arguing serious damage is being caused to the leatherback turtles that come to nest on the Guanacaste beaches of Playa Grande and Playa Ventanas.

In response to Pedro Vargas:
First, our project has a 20 year history of research efforts that have contributed to conservation of leatherbacks in Costa Rica, including the formation of the National Park, and the ELIMINATION of egg poaching, which was one of the main drivers in the population decline of these animals. Thus, our reputation for important, reliable scientific research and consistent, dedicated conservation efforts speaks for itself -in Costa Rica and around the world.

Second, as conservation scientists working with endangered species, we have a responsibility to maximize the conservation applications of our research while minimizing the impacts of that research on our study animals. The very nature of field research is such that it is impossible NOT to have some impact -however small- on one’s study subjects. Despite this unavoidable fact, we used the most widely accepted, proven technique available to us at the time of the study to attach transmitters to leatherbacks (the harness) to study their movements and the environmental influences of those movements throughout the Pacific Ocean. No tracking study had ever been conducted on this population on the scale of this one, and no tracking study had ever obtained so much crucial information to be used for conservation of leatherbacks in Costa Rican waters, and international waters as well.

Third, speaking of conservation importance, through high-level analyses of these high-quality data, we were able to outline clear, pertinent recommendations for conservation of leatherbacks in their marine habitats. In addition to egg poaching, incidental capture of leatherbacks in fishing gear also has been implicated as a major driver of this population’s decline. Thus, mitigating the interactions between leatherbacks and fishing gear is now the most important conservation issue facing us and the leatherbacks we are trying to save from extinction. The information we obtained in this study has allowed us, for the first time, to describe in great detail where leatherbacks go, why they go there, when they go there, and what can be done to keep them out of fishing gear.

Fourth, as a technical point, contrary to the claim in his post, there are currently no data clearly demonstrating adverse impacts of the harnesses on leatherbacks. The only studies that have explored this possibility have arrived at tentative, suggestive conclusions that harnesses might result in slightly slower travel rates or might be related to earlier start of migration. What is needed is a rigorous test of various techniques to figure out what the impacts actually might be.

Fifth, we have identified almost 2000 individual leatherbacks over the past 15 years of monitoring, but have seen fewer than 500 return to the beach after being counted for the first time. Thus, we have an unfortunately, but consistently, low rate of return of our turtles (about 25%). In fact, during the years that we put harnesses on turtles, we counted 417 individual turtles, of which only 18% have returned so far. The turtles that we put harnesses on (46 total) are in the proportion that haven’t returned yet, but still might. Leatherbacks take between 2 and 7 years to return to the beach to nest, and in some cases, we’ve recorded turtles returning after intervals of more than 10 years! Everyone can rest assured that when these turtles come back, our patient field biologists will be waiting to count them.

The take-home message is this: we care about saving these turtles more than almost anyone, and we always try to do the best job we can to find out what we need to know to save them, and to take the actions necessary to save them. We hope that others will join us in saving the leatherbacks in the Eastern Pacific!

i think turtles are the most awesome animals i have two myself but believe me they’re much much much smaller than this one i wish i could do all the hard work you guys did for that turtle i would risk my life to save a turtles and i am not kidding i love turtles so much i could spend a whole hour talking or typing about turtles there incredible animals in my point of view they;re better then dogs and any other animals when i hope to grow up to be just like those guys but only a girl well thanks for what you guys did thats what everyone should do pitch in just a little but what you guys do i a big step into helping the earth but i dont think theres enough people in the world that will actually help all they want to do is build and make bunches of money you can do that but you can do that by helping the environment and you can make just as much money but i like to do it for fun or for free well i better wrap this up thanks for all that you did thanks very very very very very very much bye bye now 8)

Thanks for your great comment, Danielle! Nice words of support go a long way for us folks working hard to save these animals and their habitats. And just through your enthusiasm and personal choices, you are already part of the team, helping the conservation efforts! Keep it up!

During a recent off shore fishing trip (August 21, 2008) I hooked into an extremely enormous sea turtle of approximately nine feet long, with a head the size of a cow. I had no idea that a sea turtle could be that large, and that far north. We were 30 miles south of Block Island, RI. I just wanted to know how large the largest known leatherback turtle is, and what you think he was doing this far north. Love the research you are doing, keep the info rolling.
Peter
PS. The turtle was released unharmed

Hey Peter H. – I was with some friends jet sking back from Block Island, RI Today. I was about 10 miles out and saw what had to be the same turtle!! I was HUGE!!! at leave 9-10 feet and looked wicked bada$$… wish I had my camera with me!

That would be a leatherback! The largest on record was found on the coast of Wales, entangled in a net. It was a male leatherback that measured 2.8 m (almost 10 feet) long and weighed more than 900 kg (2100 lbs.). There really haven’t been any records close that monster. The biggest records we hear of in the Atlantic and Caribbean are not quite 2m (7ft) long over the shell and probably weigh 700-800 kg (>1500 lbs). Not small, that’s for sure!

The farthest north that a leatherback has been confirmed is up off of Norway, at appx 72 degrees North latitude! There are also reports of them in Alaska and swimming around ice floes in northern Canada. In fact, there is a great research crew based in Nova Scotia who work with local fishermen every summer studying leatherbacks in the ocean on the Scotian shelf. Leatherbacks are off New England, Nova Scotia, Newfoundland every summer around the same time (August-September). Look up the Canadian Sea Turtle Network for more info.

So how did you guys get it unhooked? What were you fishing? Nice work releasing it unharmed, and thanks for sharing. Keep that camera handy next time, just in case!

And thanks for your interest in our research. It sure isn’t a bad job!